Perforated drain hole liner



Sept. 3, 1957 1. A. zuBLlN 2,804,926

PERFORATED DRAIN HOLE LINER 2 Shee'ts-Sheet 1 Filed Aug. 28, 1953fob/MA. Zmbzw 13%@ aw, www

ATTORNEYS sept. 3, 1957 J. A. ZUBUN 2,804,926

PERFORATED DRAIN HOLE LINER Filed Aug. 28, 1953 2 Sheets-Sheet 2INVENTOR A Zll/p,

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ATTORNEYS nited States ater PERFORATED DRAIN HOLE LINER John A. Zublin,Los Angeles, Calif.

Application August 28, 1953, Serial No. 377,183

4 Claims. (Cl. 16d-50) This invention relates generally to a perforatedliner for insertion into deviating drain holes which have beenpreviously drilled. More specifically,- t'he invention relates to aflexible perforated drain hole liner which may be expeditiously variedin length Within predetermined limits so as to accommodatecorrespondingly different drain hole lengths such that it may beproperly adjusted to correspond to the length of the deviating drainholes in which it is positioned.

In recent years it has become the established practice to drill a seriesof drain holes deviating from a vertical main well bore into thesurrounding oil bearing formations to substantially increase the oilproduction from a single well. In many oil elds perforated liners,prefabricated liners or gravel packed liners have been installed in thevertical well bores to filter from the oil the floating sand and otherimpurities which travel with the oil to the well bore. These structuresprevent the tubing and pumping means for the well from sanding up, whichwould naturally interrupt the continuous steady oil production of thewell. Similarly, flexible, perforated liners must be inserted into thecurved bores of drain holes which deviate from the initial main wellbore, such ilexible perforated liners in the drain holes also `helpingto prevent sanding up of the equipment used in recovering oil from thewell.

In providing drain holes deviating from the main straight well bore,such drain holes will take off from the main well bore at diierentpoints along the length of the well bore extending out into the oilbearing strata to increase the productivity of the well by promotingdraining of the oil from the oil bearing strata through which the wellbore extends. With these many drain holes deviating at various pointsalong the length of the main well bore, it is necessary that aperforated liner be inserted in each of the deviating curved bores toreceive the oil as it drains from the particular stratum in which thecurved bore is located and conduct it to the perforated liner insertedin the vertical well bore.

To eifectively conduct the oil from these drain holes the curved linermust be of the proper length so as to t accurately into the drain holein such a manner that the end ther-cof is at the furthermost outer pointalong the length of the drain hole and its inner or upper end lies asclose as possible to the Vertical liner. This inner end, however, mustnot protrude into the vertical bore sol as to obstruct the free movementof a liner being inserted into the vertical bore following the insertionof the curved perforated liners in each of the many drain holes;

It has been found to be extremely diicult to accurately determine thelength of the curved flexible perforated liner necessary to mosteffectively occupy the full length of a particular drain hole and yetnot protrude into the vertical well bore so as to obstruct or hinder theinsertion ofthe main perforated liner into such vertical well bore. Thelength of a drain hole startingfrom a Yvertical bore atdepths rangingfrom 3,000 to 9,000 feet can only be determinedby measuring the lengthof the flexible drill 'pipe which has entered into the deviating'bore.-`Unfortunately the take-off point of the curved bore cannot always beaccurately determined, since the drill bit, pressed against the wall ofthe straight bore by the resiliency of the curved drill guide, may haveslipped several feet before it actually takes hold of the formation toform a definite shoulder from which the deviating curved bore proceeds.

For obvious reasons of economical operation, drain holes deviating froma vertical well bore are not always made of the same length. Oil bearingyformations are frequently interrupted by layers of hard shale which donot contain oil, so that continued drilling of the deviating drain holeinto such layer of shale becomes a waste of time and money. Thus it hasbecome the practice to employ a shorter drain hole when such layers areencountered and spend the time saved in drilling more or longer drainholes in other more prolic layers of oil-bearing formation.

In the light of the above-noted problems encountered in applyingperforated liners to previously drilled drain holes deviating from avertical bore, it can well be appreciated that standard unit lengthperforated liners produced in a factory away from the oil field cannotbe quickly adjusted on the derrick floor to accommodate the differencesin length encountered in the various drain holes. Nor is it entirelypractical to attempt to adjust the iiner length on the derrick floorsince the drain hole length cannot be determined with complete accuracy.Accordingly, the invention hereinafter described provides a flexibleperforated liner which is adjustable in situ to accommodate the variouslengths of drain holes encountered in actual practice.

lt is a principal object of this invention to provide a perforated linerinsertable into a deviating drain hole bore so that the uppermost end ofsuch liner'is properly aligned with the mouth of the drain hole, whilethe lower end thereof contacts the outermost end of the drain hole andthus utilizes the entire drain hole length for recovery of oil from theoil bearing strata. v

It is another object of this invention to provide a flexible perforatedliner which is self-adjusting to the unknown length of the drain holeafter the liner has been inserted thereinto and will securely positionitself in the drain hole with one end seated in the mouth of the drainhole adjacent the main well bore.

It is also an object of this invention to provide a flexible drain holeliner having a telescoping section at one end thereof tO enablevariation of the length of such liner to accommodate the particularlength of drain hole with which such liner is associated.

It is a further object of this invention to provide a flexibleperforated drain hole liner lowerable into a curved drain hole having ahead at the upper end thereof which snugly engages with the mouthof thedrain hole to retain the liner properly positioned within the drainhole.

The foregoing objects of the present invention and others which will beapparent from the description of a preferred embodiment set 4forthhereinafter, are obtained through provision of the variable length linerconstruction. The details of the invention will become apparent as thedescription proceeds, which will be given by reference to theaccompanying drawings which form a part hereof, and in which:

Figure 1 illustrates the positioning of the adjustable drain hole linerof the present invention in an oil well drain hole deviating from themain well bore.

Figure 2 illustrates the relationship between the inserted perforateddrain hole liner and main well bore perforated liner subsequent to theinsertion of such liners into the well bores.

Figure 3 is a detailed view partially in section illustrating thelength-adjusting structure of the perforated liner.

Figure 4 is a sectional view taken on line 4-4 of Figure 2.

In general it may be stated that the invention hereinafter specificallydescribed embodies an assembly of one perforated liner sectionpositionedinside another somewhat larger perforated liner section. Aplurality of standard unit lengths of the smaller diameter liner areconnected together to make up a perforated liner section approximatingthe overall length, but less than the length, of the drain hole in whichthe liner assembly is to be inserted. The balance of the lengthnecessary for the liner assembly to completely occupy the full length ofthe drain hole is supplied by the larger diameter perforated linersection which is slidably mounted to telescope over the upper end of thesmaller diameter perforated liner section. A shear pin is utilizedduring the lowering of the liner into the deviating drain hole tomaintain the larger telescoped section in extended position relative tothe smaller diameter perforated liner and permit desired orientation ofthe assembly so as to properly guide the lower end thereof into thedeviating drain hole.

When the lower end of the liner assembly, which is the end of the seriesof unit lengths of interconnected smaller liners, strikes the bottom ofthe drain hole, the Weight indicator on the derrick floor provides anindication to the operator that the bottom of the drain hole has beenreached as shown by the reduced Weight indication. The drill string,which suspends the flexible liner assembly, is lowered for a furtherdistance to cause the shear pin to be sheared and allow the larger linersection to slide over the upper end of the smaller liner section intothe drain hole until the upper end of such larger liner section becomesseated within the mouth of the drain hole. Such fitting of the upper endof the larger liner section in the mouth of the drain hole will create asecond weight change on the weight indicator on the derrick floor, andas such will inform the operator that the liner has been seated and thatthe means used to lower and guide the liner into the drill hole can bewithdrawn from the vertical well bore.

The seating means for the upper end of the larger liner section whichtelescopes over the end of the smaller diameter perforated liner sectionconsists largely of ribs or fins on the outer end of the liner, of suchdimensions that they position the head of the larger diameter linersection securely within the mouth of the drain hole while preventing anydownward slippage of the assembly.

Since the liners must be lowered through a vertical straight bore beforeentering the curved bore of the drain hole, it is possible to eitherutilize a normally curved flexible liner which is forcibly loweredthrough the straight vertical bore and allowed to assume its normalcurvature on entry into the :curved drain hole, or to utilize anofrmally straight liexible liner which is lowered freely through theyvertical straight bore and forced into the curved deviating drain holeto assume the curvature of such drain hole. In the actual practice ofinserting perforated liners into previously drilled drain holes, due tothe problems encountered in such operations, the use of a normallycurved resilient perforated liner is more desirable than the use of anormally straight resilient liner.

Hereinabove only a general description of the significant features ofthis invention has been set forth, the basic elements of which it willbe readily appreciated are susceptible of wide variation within thescope of this invention. Broadly, it may be stated that the apparatus ofthis invention is characterized by a perforated liner assembly of anormal unit length but adaptable to drain holes of different lengths bya slidable telescopic construction between the parts of the flexibleliner assembly.

Referring to the specific embodiment illustrated on the drawings, Figurel illustrates a main well bore and a drain hole 11 deviating from themain well bore.

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A flexible perforated liner assembly is shown being positioned in thedrain hole 11 by being lowered thereinto by means of a suita'bleflexible drill string 12 controlled from the well derrick floor.

The flexible perforated liner assembly comprises a relatively smalldiameter perforated liner section 13 which is made up of a plurality ofstandard unit length sections suitably secured together to approximatethe required length of drain hole liner necessary to completely fill thedrain hole in which it is to be inserted.` A larger diameter perforatedliner section 14 telescopically engages one end of the liner section 13and thus is slidable thereover to vary the over-all length of ytheflexible liner assembly.

The perforated liner sections 13 and 14 are provided with perforations Pto admit oil draining from the surrounding formation into `the liner.These liner sections may be made liexible by cutting slots in pipesections in a form such as illustrated and disclosed in my copendingapplication, Serial No. 377,184, tiled August 28, 1953.

The opposite end of the series of interconnected liners which make upthe smaller perforated liner section 13 is provided with a plug 15 whichmay be suitably threaded into such end to fclose off the end of suchliner section and in use serve as an abutment to engage the end of thedrain hole 11. The upper end of the liner section 13 positioned withinthe liner section 14 has threaded thereonto a collar 16 which cooperateswith a similar collar 17 threaded into the lower end ofthe larger linersection 14 to retain the two sections 13 and 14 against disengage mentand limit the elongation of the liner assembly.

A shear pin 18 is inserted into aligned holes provided, respectively, inthe collar 17 and the adjacent end of liner section 13 when the linerassembly is at its maxi-mum length. This shear pin functions to retainthe flexible liner assembly in its extended longest position duringlowering of the assembly into position into the deviating drain hole.Upon engagement of the plug 15 carried by the outer end of liner section13 with the end of the drain hole, continued lowering of the assemblywill cause the shear pin 18 to be sheared and the larger liner section14 to telescope over the end of the liner section 13 while the collar 17slides along the outer surface of the lirici' section 13. Thus the linerassembly will be appropriately shortened to adjust itself to the lengthof the drain hole in which it is being positioned. The sliding fitbetween the liner section 13 and the inner bore of collar 17 precludesany undesirable entry of sand particles into the perforated linerassembly.

The upper end of the outer larger liner section 14 carries a head 20suitably threaded thereunto. The head 20 is lprovided with a pluralityof longitudinal radial fins 21 at circumferentially spaced positionsalong one side 0f the head. These fins are tapered at both ends and aremade of such a size according to the diameter drill bit used in drillingthe drain hole so as to t snugly into the mouth of the drain hole 11 inproperly positioning the liner assembly therein. A tapered hook-like rib22 extends radially from the side of the head 20 opposite the spacedlongitudinal fins 21 and is shaped so as to engage the formation withinthe well immediately at the junction of the deviating drain hole 11 withthe main bore hole 10. Thus this rib 22 engages the shoulder at point Aso as to retain the head 20 and the liner sections 13 and 14 suspendedtherefrom in fixed position within the drain hole 11.

The head 20 is provided with a plurality of small openings 23 whichallow the oil to flow from the perforated liner assembly outwardly intothe main well bore.. The head 20 has formed therein a socket 24 which isengaged by a stud 25 secured to the lower end of Vthe flexible drillstring 12 which is utilized in lowering the perforated liner assemblyinto position in the drain hole 11. A shear pin 26 interconnects thesocket 24 in the head and stud 25 through aligned holes provided in therespective members to be interconnected.

It will be readily appreciated that the socket 24 shown as being locatedin the head 20 may, if desired, be formed in the lower end of the drillstring 12. With such an arrangement the stud would be carried by thehead 20 so las to engage the socket on the end of the drill string andbe retained thereon by a shear pin in a manner such as illustrated onthe drawings. Likewise it will be recognized that within the scope ofthis invention any suitable connecting means may be utilized to suspendthe liner assembly from the end of the drill string which isdisconnectible from such assembly to permit withdrawal of the exibledrill string after positioning of the liner -assembly in a drain hole.

The perforated liner assembly is lowered into its fully seated positionwithin the drill hole 11 by shearing the pin 18 and telescoping theliner sections 13 and 14. The rib 22 seats on the shoulder at point Aand additional weight applied to the drill string 12 effects shearing ofpin 26. The flexible drill string 12 can then be raised and removed fromthe well bore in readiness for insertion of the next perforated linerinto another drain hole or insertion of a vertical perforated liner intothe well bore as is done after all of the drain holes drilled have beenequipped for flexible perforated liner assemblies.

The embodiment of the invention illustrated on the drawings shows shearpins 18 and 26 to releasibly retain the liner assembly in its extendedcondition and detachably connect the assembly to the end of the drillstring used in lowering the assembly into the drain hole. It will bereadily recognized, however, that within the scope of this invention anysuitable device or devices may be utilized with the telescoping linerassembly to perform the function of these two shear pins.

Since the socket 24 after removal of the stud 25 is exposed and openedat its upper end a perforated partition 27 is disposed across an end ofthe socket 24 to prevent the entrance of packing gravel 31 which isapplied around the perforated liner 30 at its junction with the upperend of the flexible perforated liner assembly. Furthermore, to preventsuch gravel packing from entering the drain hole proper and lling thespace around the perforated liner sections 13 and 14 transverse baleplates 28 are suitably secured between the frns 21.

In oil well drilling operations it may be necessary to ll the annularspace between the vertical perforated liner 30 and the walls of the wellbore 10 with gravel. However, it is desirable to prevent such gravelfrom entering into the drain hole so as to ll in part of the voidbetween the flexible liner and the deviating bore. The baa plates 28thus allow the gravel to ll all of the empty space created adjacent thejunction of the deviating drain hole with the main well bore withoutentering the drain hole proper. The openings 23 in the head 20 permitthe free ow of oil from the flexible perforated liner assembly throughthe gravel ll into the openings of the vertical perforated liner 30.

rI'he method of positioning the perforated exible liner assemblydescribed hereinbefore comprises lowering the assembly, suspended fromthe end of a exible drill String, to the location of the 'deviatingdrain hole in which the liner is to be inserted, orienting the linerassembly so the lower end will be directed to enter the drain hole, andlowering the liner assembly into this drain hole until the end thereofengages the outermost end of the drain hole. Continued lowering of theassembly effects telescoping of the two liner sections so that thelength of the liner assembly is effectively shortformed between thevertical well bore and the drain hole. Further lowering of the flexibledrill string effects shearing of the interconnecting pin suspending theliner assembly from such drill string, `and thus severs the connectionbetween these members to enable withdrawal of the flexible drill stringfrom the well bore.

Having thus described my invention, what I claim is:

l. A perforated liner assembly for insertion into a curved oil welldrain hole comprising, a plurality of perforated pipe sectionstelescopicallyengaged so as to be slidable into one another to vary theoverall length of the 'assembly to accommodate the drain hole lengthinto which the assembly is to be inserted, engaging means carried by theadjacent ends of said sections to maintain said sections telescopicallyinterconnected, and a head secured to the outer end of one of saidsections for engaging the mouth of the drain hole into which theassembly is inserted to retain said assembly properly positioned withinthe drain hole, said head having a radial rib extending from one sidethereof to engage the shoulder at the junction of the curved drain holeand the well bore and at least one radial lin extending from theopposite side of said head to engage the drain hole bore to positionsaid head in the mouth of said drain hole.

2. A perforated liner assembly as recited in claim 1 wherein said headis further provided with perforations to permit free egress of oil fromthe liner assembly and transverse baflles positioned intermediate theradial rib Iand radial iin to prevent packing ll in the main well borefrom entering the curved drain hole bore.

3. A perforated liner assembly as recited in claim 1 wherein releasablecoupling means are provided onsaid head for detachably suspending saidassembly from a drill string utilized in lowering said assembly throughthe main bore hole into position within the drain hole bore.

4. A flexible perforated liner assembly for insertion into a curved oilwell drain hole deviating from a well bore of a diameter substantiallylarger than the diameter of the drain hole comprising at least oneperforated exible pipe section having an outer diameter smaller than thediameter of the drain hole, a head secured to one end of said pipesection and having means imparting a larger lateral dimension theretothan the diameter of said pipe section and the drain hole so as tosubstantially ll the mouth of the drain hole when in use, said means atthe surface thereof which advances into the drain hole having a beveledportion extending inwardly toward the peripheral surface of said pipesection so that the head may be snugly engaged in the drain hole at thejunction of the curved drain hole and the well bore to securely retainsaid assembly positioned with the end thereof immediately adjacent the'mouth of the drain hole, said head having perforations communicatingwith the interior of the pipe section and permitting egress of oil fromthe drain hole while preventing extraneous material from entering thedrain hole and liner assembly, and means on said head for Vdetachablyconnecting said assembly to the end of a drill string to lower saidassembly into position within the drain hole and release said assemblyfromA the drill string after it is positioned within the drain hole.

References Cited inthe iile of this patent UNITED STATES PATENTS1,886,820 Lee NOV. 8, 1932 2,365,052 Chamberlain Dec. l2, 1944Y2,397,070 Zublin Mar. 19, 1946 2,452,920 Gilbert Nov. 2, 1948 2,664,270Zublin .L Dec. 29, 1953

